help.c

linux 下用c++ 开发的一个小型数据库系统

#include <sys/types.h>
#include <functional>
#include <string.h>
#include <stdio.h>
using namespace std;

#include "error.h"
#include "utility.h"
#include "catalog.h"

// define if debug output wanted


//
// Retrieves and prints information from the catalogs about the for the
// user. If no relation is given (relation is NULL), then it lists all
// the relations in the database, along with the width in bytes of the
// relation, the number of attributes in the relation, and the number of
// attributes that are indexed.  If a relation is given, then it lists
// all of the attributes of the relation, as well as its type, length,
// and offset, whether it's indexed or not, and its index number.
//
// Returns:
// 	OK on success
// 	error code otherwise
//

const Status RelCatalog::help(const string & relation)
{
  Status status;
  RelDesc rd;
  AttrDesc *attrs;
  int attrCnt;  
 
  if (relation.empty())
    return UT_Print(RELCATNAME);
 
  if ((status = relCat->getInfo( relation, rd)) != OK) return status ;

  if ((status = attrCat->getRelInfo( relation, attrCnt, attrs)) != OK) return status ;

  int i ;
  cout<<"\n" ;
  printf("%-*s", 25, "RelName") ;
  printf("%-*s", 25, "AttrName") ;
  printf("%-*s", 11, "Offset") ;
  printf("%-*s", 10, "Type") ;
  printf("%-*s", 9, "Length") ;
  
  printf("\n") ; 
  for(i = 0; i < 80; i++)
    cout<<"-" ;
  
  printf("\n") ;
  for (i = 0; i < attrCnt; i++){
    printf("%-*s", 25, attrs[i].relName) ;
    printf("%-*s", 25, attrs[i].attrName) ;
    printf("%-*d", 11, attrs[i].attrOffset) ;
    switch(attrs[i].attrType){
      case STRING :
         printf("%-*s", 10, "STRING") ;
         break ;
      case INTEGER :
         printf("%-*s", 10, "INTEGER") ;
         break ;
      case FLOAT :
         printf("%-*s", 10, "REAL") ;
         break ;
    }
    printf("%-*d\n", 9, attrs[i].attrLen) ;
  }
  
  printf("\n\n  %d  record (s)  selected!\n", attrCnt) ;
  delete [] attrs ;
  return OK ;  
}